There are a number of known techniques for determining the position of an apparatus using radio frequency signals. Some popular techniques relate to use of the Global Positioning System (GPS), in which multiple satellites orbiting Earth transmit radio frequency signals that enable a GPS receiver to determine its position. However, GPS is often not very effective in determining an accurate position indoors.
Some non-GPS positioning techniques enable an apparatus to determine its position indoors. However, some of these techniques do not result in an accurate position being determined, and others are too complex for use simply in a portable apparatus. For example, the amount of processing power required to perform the technique may be impractical to provide in a portable apparatus, which may need to perform concurrent functions.